In recent years, as a wristwatch, a so-called radio-controlled timepiece that receives an external radio wave including time information and corrects a time retained internally is becoming widespread. In general, the radio wave received by the radio-controlled timepiece is a long-wave-band radio wave called a “standard wave”, and has a disadvantage of geographical limitations and a long time required for reception due to use of a low-frequency carrier wave.
In contrast, there is proposed a radio-controlled wristwatch that receives an ultra high frequency used in a global positioning system represented by the Global Positioning System (GPS). For example, Patent Literature 1 discloses a wristwatch with the GPS that receives a satellite signal from a GPS satellite and corrects the time based on GPS time information included in the satellite signal.
Further, Patent Literature 2 discloses a car navigation device that receives the satellite signal from the GPS satellite, in which a current cycle number of WN is detected by referring to a cycle number of WN recorded in a map information recording medium or leap second information.